In the above technical field, non-patent literatures 1 and 2 disclose techniques of enhancing a target signal and suppressing an interfering signal by processing a plurality of sensor signals to generate an enhanced target signal, suppressing the target signal to generate a pseudo interfering signal in which an interfering signal is relatively enhanced, and subtracting a component correlated with the pseudo interfering signal from the enhanced target signal.
In these techniques, directivity is formed using a phase difference between signals based on a difference in spatial position between a plurality of sensors, and a specific signal is enhanced or suppressed based on the formed directivity.
Furthermore, non-patent literatures 3 and 4 describe arrangements obtained by combining the techniques of non-patent literatures 1 and 2 in a plurality of frequency bands from a low band to a high band using a plurality of arrays with different sensor intervals.